Do you reload? If yes, simply run .308/7.62x51 brass into your 7.5 French full length sizing die and you have reloadable French brass. The neck will be shorter than normal French brass, but it reloads and shoots just fine, and never needs trimming. Friends and I did it that way for a few years.
PS We never had split cases or problems doing this. We had the French 36 bolt guns, never tried it in semi-autos, and generally used milder (not full power) loads with cast bullets and jacketed bullets.